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Thermal Performance of Light-Frame Assemblies I n t e r n a t i o n a l Building series NO. 5 Introduction “A man’s home is his castle” during the sweltering days designers must understand knowledge of the thermal is an old familiar phrase, but of summer. Today’s home the impact of the materials performance of wood and if truth be told, the buyers demand energy and assemblies used on other framing techniques. castles of old were cold and efficient houses with high thermal performance. draughty. Today’s homes are insulation values. “Lowering now havens of comfort with energy use” has become Because of its long history of designers and builders to efficient central heating the goal as the cost and use, wood-frame construction select construction techniques environmental implications has well established insulating that provide the best thermal of energy use are considered. properties and record of performance. systems and well insulated building envelopes. We This information will assist performance. The effect of count on the walls and roofs of our houses to keep the Insulation levels are now other construction systems on heat in during the winter being required by many code insulation properties is not widely months and the heat out authorities. Stricter thermal known or understood. This requirements mean that publication will examine current Thermal Performance In temperate climates, flow to and from the building becomes less dense and rises, results in convection, air almost 20% of total energy cannot be stopped altogether, and cooler air is drawn in to fill leakage can also move directly consumption is used for the but can be minimized by the space left by the displaced through small openings into heating, cooling, and lighting using a combination of heated air. walls or roofs. This can carry of residential buildings. This materials that resist heat flow. energy use is costly but the Heat is transferred in 3. Radiation occurs when one use of selected materials the following ways: object transfers heat to another and lead to condensation. object by releasing heat waves. All four types of heat transfer help to improve the overall 1. Conduction occurs in a For example, the sun produces affect buildings. However, most thermal performance of solid material when the radiant energy that heats the heat loss in tightly constructed our buildings. molecules are excited by a heat earth. Radiation can affect buildings occurs by conduction source on one side of surface temperatures of through the building the material. These molecules buildings, but affects heating components. To maximize transmit energy (heat) to the requirements mainly through energy efficiency, building cold side of the material. glass windows and doors. assemblies must be designed and building systems can 2 water vapour into wall cavities Heat Transfer Defined Heat always moves from a warm area to a cold area. Heat flows from the interior through the building envelope to the exterior in the winter, and from the exterior to the interior in the summer. Heat I n t e r n a t i o n a l Building series NO. 5 Conduction occurs primarily using framing materials that through the foundation and 4. Air currents can carry hot resist heat flow, and must framing members in buildings. or cold air and depend on the include continuous air barriers, The rate of heat flow depends pressure differences between insulation materials, and on the materials used. the interior and exterior of weather barriers to prevent air the building, as well as air leakage through the building 2. Convection is the movement leaks in the building envelope. envelope (see Figure 1). of air that occurs as heated air Although this sometimes An air barrier is a membrane In typical frame construction, air pressure differences from Insulating materials placed that restricts the migration of air leakage is possible where services, wind, ventilation, and air within the wall, roof, or floor into and out of a building vents, and pipes traverse exterior movement. For example, a cavities slow the rate of heat envelope. This is to control heat walls and ceilings. The applied 0.15 mm polyethylene transfer from warm to cool areas. loss through uncontrolled air air barrier must be durable, membrane placed on the Their efficiency is based on leakage, but also to ensure that strong and continuous through- inside of framing members, reducing conduction of heat unwanted moisture is not carried out the building envelope, and caulked, and tightly held in through air pockets in their into wall or roof openings. properly installed to resist the place by the application of composition, and by minimizing gypsum board constitutes an convection by keeping the air air barrier. pockets small. Common insulating Figure 1: Maximizing Energy Efficiency Another example is a spunbonded polyolefin materials are made from various “housewrap” membrane with materials including mineral or taped joints, applied to the glass fibers and expandable foams. outside of wall sheathing. A weather barrier is a A continuous air barrier applied over wood-framing and insulation significantly improves the thermal performance of a building by reducing air leakage. Overlapping of the air barrier, together with caulking around this ceiling air vent, helps to prevent air leakage through the building envelope. In colder climates, both the membrane placed on the interior polyethylene exterior sheathing as a first membrane and the exterior defense to protect the envelope “housewrap” membrane are from wind, rain, and snow. In used together. That is because some cases, this includes the the polyethylene air barrier is “housewrap” type membrane or also a vapour barrier and the other types of sheathing paper exterior “housewrap” is also a used as an air barrier, but such weather barrier. In cold membranes must be installed climates, vapour barriers are continuously with flashing placed on the warm side of the around wall openings to ensure insulation to prevent vapour good drainage. from diffusing through the interior wall or The obvious consequence of ceiling finish, and then cooling using assemblies with poor thermal and condensing within the wall performance is the requirement or roof assembly. for additional energy to heat and cool a building. In addition to A weather barrier applied to the exterior sheathing prior to siding materials, acts as an additional barrier against wind, rain and snow. Source: John W. Wren Holdings Ltd. T h e r m a l The polyethylene should not be the negative environmental used on the outside of houses impacts, this increased use of in colder climates because it energy translates into an would trap any moisture in the increased cost to the building wall assembly. The “housewrap” owner that continues for the life type material is not a vapour of the building. Proper design barrier, making it suitable techniques must be used to for use on the outside of increase the energy efficiency the house. and durability of a building. p e r f o r m a n c e o f L i g h t - F r a m e A s s e m b l i e s 3 Figure 2: Microscopic Wood Structure Wood: A Natural Thermal Insulator construction techniques are Wood is a natural thermal within a wall, roof, or floor insulator due to the millions of tiny air pockets within its cellular structure (see Figure 2). Since thermal conductivity increases with relative density, wood is a better insulator than dense materials. based on the inclusion of efficient insulating products Summerwood structure (see Figure 3). Due to its air pocket composition, wood is also an Springwood effective acoustical insulator and its structure helps to dampen sound vibrations. Softwood has about one half Figure 3: Thermal Resistance of Common Materials (RSI/mm) the thermal insulating ability of a comparable thickness of fiberglass batt insulation, but about 10 times that of concrete 4 and masonry, and 400 times that of solid steel. However, although wood has the best insulating properties of the primary framing materials, wood Sheet steel no significant resistance Concrete0.001 Lumber and structural wood panels 0.009 Gypsum board 0.006 Fiberglass insulation 0.022 Mineral fiber insulation 0.024 Source: Canada Mortgage and Housing Corporation I n t e r n a t i o n a l Building series NO. 5 Effect of Framing on the Insulating Value The resistance to heat flow of transfer than in the spaces But the thermal performance of between the members to building envelope assemblies between the framing members. an assembly depends on the determine the overall resistance depends on the characteris- The framing members lower the combined effect of the framing to heat flow of the assembly, tics of the materials used. thermal efficiency of the overall and insulation. The thermal expressed as the effective RSI- The ease with which the wall or ceiling assembly. The rate properties of the framing value. The effective RSI-value can materials resist heat flow is of heat transfer at these locations materials, which can account for be used to compare the thermal called the thermal resistance depends on the thermal or insulat- 20% or more of the surface area resistance of different systems. (RSI). The thermal resistance ing properties of the framing of a wall, can have a significant is expressed as an RSI-value with units of m2 oC/W. The material. The higher rate of heat effect on the thermal resistance of The overall thermal efficiency transfer at framing members is an assembly. New energy codes of wood-frame assemblies is higher the RSI-value, the called thermal bridging. recognise this and require that the lowered by the amount of area effective RSI-value be used to occupied by the framing meet their requirements. members. For most wood-framed higher the resistance to heat flow. The thermal trans- The insulating value of an mission (U) is the inverse of assembly has traditionally been the thermal resistance of expressed in terms of the nominal The effective RSI-value is the value is approximately 90% of the assembly. RSI-value that is specified on the measured thermal resistance of the RSI-value of the cavity insulation materials to be used an assembly. It takes into insulation. Insulated assemblies are not in the assembly. In other words, consideration the thermal effect usually homogeneous throughout the RSI-value was based on the of all the materials in the In steel-frame assemblies, heat the building envelope. In wood or insulation alone. In general, this assembly. In framed assemblies, does not flow in parallel paths steel-frame walls or roofs, the approximation works well to the framing members act as because steel has a high thermal framing members occur at regular express relative insulating thermal bridges. Their effect is conductivity. Heat flows not only intervals, and, at these locations, properties only if the framing calculated and combined with through the assembly from the there is a different rate of heat systems are the same. the insulating value of the spaces inside to the outside of the assemblies, the effective RSI- building envelope, but also moves from the centre of the insulated cavity to the framing Figure 4: Heat Flow Through Wood and Steel members. Heat flow is therefore concentrated at the steel stud (see Figure 4). Steel Stud Wood Stud The steel framing member has a much larger effect on the transmittance of heat through the assembly than its own width, and acts as a thermal bridge through the insulation. This thermal bridging results in an effective RSI-value for steel-framed assemblies of 50 to 60% of the RSI-value of the cavity insulation. Note: Heat flow lines each represent an equivalent amount of heat flow through wall. T h e r m a l p e r f o r m a n c e o f L i g h t - F r a m e A s s e m b l i e s 5 Energy Conservation and Wood Frame Construction Wood frame construction There are two aspects to The indirect energy is the energy Council has published an techniques have evolved over energy conservation in use associated with processing, Environmental Impact Study that the past few decades buildings: embodied energy, transporting, converting and demonstrates the impact of to meet new energy and operating energy. delivering fuel and energy to its embodied energy of structures conservation targets. point of use. on the environment in terms of For example, a program called The recurring embodied energy global warming potential, air and R-2000 was developed by Natural Resources Canada in partnership with Canada’s residential construction industry, to set a new standard for energy-efficient housing. Building to R-2000 specifications exceeds building code requirements, consuming less energy and producing less greenhouse gases. R-2000 homes also incorporate advanced fresh air ventilation systems, window performance Embodied Energy water pollution, and solid wastes. in buildings represents the non- The "embodied energy" in buildings means the energy consumed in the acquisition of raw materials, their processing, manufacturing, transportation to the site, and construction. The initial embodied energy has two components. The direct energy, that is the energy used to manufacture and transport building products to the site and to construct the building. renewable energy consumed to Today’s comparisons of embodied maintain, repair, restore, energy and the operating energy refurbish or replace materials, of buildings over their life-cycle components or systems during are dominated by the operating the life of the building. component. However, as buildings become more energy-efficient While it is simpler and more and as we move away from fossil common to focus solely on the fuels as an energy source, conservation of operating the ratio of embodied energy energy, the effects of embodied to lifetime operating energy energy can be significant in consumption becomes more structures. The Canadian Wood significant. requirements, and environmentally improved Table 1: 1970 Construction vs R-2000 Design building materials. Another program sponsored by the Government of Canada Floor area 207.4m2207.4m2 The Super E House Program, Design Life 30 years 30 years supported by Canadian Primary structure Wood frame construction, concrete basement Wood frame construction, concrete basement Envelope 38 x 89 mm studs (GRN), RSI-2.1 fibreglass batt insulation 38 x 140 mm studs (KD), RSI-3.5 fibreglass batt insulation Windows Wood windows, standard double glazed PVC windows, low-E, double glazing, argon fill Exterior cladding Brick Brick Roofing System Wood frame truss, asphalt shingle, RSI-3.5 fibreglass batt insulation Wood frame truss, asphalt shingle, RSI-8.8 fibreglass batt insulation is the Super E House Program for countries other than Canada. 6 Building 1970’s ExampleR-2000 Design ComponentConstructionExample technology, expertise and training, has been introduced into the United Kingdom, Ireland, and Japan. For more information on the R-2000 Program and the Super E House Program visit http://www.oee.nrcan.gc.ca/r-2000 and http://www.super-e.com, respectively. I n t e r n a t i o n a l Building series NO. 5 Operating Energy The AthenaTM Sustainable Operating energy efficiency The annual space heating for Materials Institute compared in residential and commercial the R-2000 home is only 27% The need for saving energy the environmental performance buildings is greatly enhanced that of the 1970’s home (a factor by reducing operating energy including embodied in highly insulated and airtight of 4 decrease). Total R-2000 consumption in buildings is environmental effects for single- building envelope systems, high annual operating energy use is widely recognized throughout family home designs as typically performance windows, high- 42% that of the 1970’s design, the world. built in Canada from the 1970’s energy efficiency heating, cooling and the total 30-year life cycle through to the present. The and water heating equipment, energy for the R-2000 house is study was based on the "as low energy lighting and Energy- only 46% that of the 1970’s built" design of the Canadian Star home appliances. design. About half of the total In Canada, the residential energy consumption decreased by 40% over the last three decades. A life-cycle environmental impact comparison of a 1970 and R-2000 house design was done by the AthenaTM Sustainable Materials Institute in partnership with CANMET Energy Technology Centre and Natural Resources Canada. improvement in operating Centre for Housing Technology houses located on the National The increased insulation in efficiency can be ascribed to Research Council’s property in foundations, walls and attics, better envelope design, with the Ottawa, Ontario. Specifications and insulated doors and windows remainder a function of higher for the same house as it would contributes greatly to reduce the mechanical equipment efficiency. have been built in the 1970’s operating energy in buildings, were compared with today’s however, it requires the use of As noted earlier, embodied R-2000 compliant construction. more materials with a higher energy effects become more (See Table 1). embodied effect. significant as the operating energy requirements of buildings are reduced (see Figures 5). This is also influenced by the increased material requirements Figure 5: Embodied Energy vs. Lifetime Heating Energy Embodied energy 8 % to build the R-2000 home. When embodied effects are Embodied energy 23 % combined with those of space heating, the R-2000 house ends up using 60% less energy and emits 61% fewer greenhouse gases over a 30-year time period. Lifetime heating energy 92 % 1970 House 7 Lifetime heating energy 77 % R-2000 House T h e r m a l p e r f o r m a n c e o f L i g h t - F r a m e A s s e m b l i e s Thermal Performance of Wood vs. Steel Steel conducts heat 400 times U.S. by the National Association Adding insulation to the outside insulation to achieve the same faster than wood. But since a of Home Builders (NAHB) face of the steel studs will insulating value as a wood-frame steel C-channel stud is much Research Centre and the Oak contribute only its own RSI- wall with cavity insulation. thinner than a wood stud, a Ridge National Laboratory, value; it does not completely 20 gauge steel stud conducts shows that the assumption of negate the effects of the steel in Effective RSI-values for steel- approximately 10 times more parallel path heat flow does not the wall assembly, and there is framed assemblies are much heat than a 38 mm wide wood apply to steel-framed systems. obviously a cost for the extra lower than wood-framed insulation. assemblies filled with the same stud. The thermal performance of framed systems has been The laboratory tests use a hot-box studied extensively in the method which tests clear wall The Canadian National Energy assemblies require high thermal laboratory and in houses. systems that are isolated from any Codes use a rigorous calculation resistance contribution from The results demonstrate other parts of the structure. These method developed by the IRC exterior foam sheathing to achieve the superior performance tests have confirmed that steel for determining the effective the same effective RSI-values of wood framing systems. studs severely lower the effective insulation values for most of as wood-framed walls without RSI-value of the assembly. the common wall, roof and floor foam sheathing. This results in Recently, IRC measured the RSI- assembly configurations. As increased costs to achieve the value of three steel stud wall shown in Figure 6, steel framing same performance. assemblies. The research lowers the effective RSI-value determined that for the steel- of the cavity insulation by close HOT2000 is an energy analysis stud wall assemblies the effective to 50%, while wood framing program for residential buildings RSI-value is approximately half impacts the effective RSI-value developed by Natural Resources that of the insulation. In other by less than 10%. In other Canada and is available at: www. words, the presence of the steel words, a 38 x 140 mm steel- buildingsgroup.nrcan.gc.ca. The studs substantially reduces the frame wall would need an program enables designers overall performance of the additional 51 mm of foam to evaluate the energy usage of Laboratory Research Results Wood framing has a long history of use. Based on testing and performance, the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Handbook of Fundamentals, uses a procedure insulation materials. Steel-framed various building designs. whole assembly. for calculating effective thermal FIGURE 6 - Wood vs. Steel Framing - Effective Insulation Values resistance for parallel path heat flow. The RSI-value is calculated at the framing (RF ) and at the insulation (RI) and then the 3.0 is determined based on the area of each, as a ratio of the total area. Laboratory research into the performance of steel-framed walls conducted in Canada by the National Research Council’s Institute for Research in Construction (IRC), and in the I n t e r n a t i o n a l Building series NO. 5 Wood studs Steel studs 3.5 average effective RSI-value (R E ) 2.1 3.4 2.5 2.5 38 x 140, 25 mm EPS 38 x 89, 50 mm EPS 2.0 1.8 1.8 3.8 3.0 2.9 2.6 RSI-Value 8 4.3 4.4 1.3 0.9 0. 38 x 89 no EPS 38 x140 no EPS 38 x 89, 25 mm EPS Source: National Energy Code for Houses 1995 38 x 140, 50 mm EPS Field Measurement and Modelling Reports from the field Administration in Portland, indicate that the thermal Oregon on light gauge steel- performance of full scale frame houses, showed walls with steel-framed houses falls plywood sheathing and 18.5 mm short of the laboratory foam sheathing to be thermally measurements previously identical. discussed. Infrared thermography of 140 The laboratory specimens were mm walls with cavity insulation "clear" walls with no anomalies and RSI-1.1 sheathing found such as intersections, window interior-wall surface temperatures frames or door frames found of 7.3°C over steel studs when in standard construction. These the outside temperature was laboratory tests were also limited 4.4°C . The study found that the to wall sections that were heat travelled down through the issue of Energy Design doors and intersections of other thermally isolated from other steel to the foundation and up to Update, that the measured building components had parts of the structure such as the steel roof structure. infiltration rate of steel-framed on the clear wall lab tests. roof framing or foundations. The following testing was performed Laboratory testing performed on steel-framed houses, where by the American Iron and Steel the performance really counts. Institute (AISI) determined that 12.5 mm of foam sheathing Thermographic Testing Infrared thermograph shows that, compared to conventional wood-framed walls, steel framing results in major heat loss from the building shell and that this study, the steel-frame wall framed walls. effective RSI-value for the entire wall was 19% lower than clear wall values. The wood-frame wall in the channels used for top and effective RSI-value for the entire and the cavity below 1.6°C. The bottom plates in steel wall wall was 9% lower than clear thermographic field testing of construction. This provides a large wall values. The steel-frame wall actual houses shows that even number of infiltration points to effective RSI-value was 40% with 50 mm of foam the the attic. Increased air infiltration lower than the effective RSI-value temperature difference between also results from the use of "hat" for the wood-frame wall when the steel stud and the cavity channels used to reduce thermal the entire wall was considered. is 2.3°C. bridging and sound transmission. be significantly worse than the improved the thermal measured laboratory performance. performance of the attic. The use of the channels creates In summary, the report concluded a slot open to the attic down the that the effect of construction full length of the wall allowing for features, such as intersections of increased air flow. windows, doors, walls and also connections with roofs and Temperatures measured at steel by the Bonneville Power infiltration rate of wood- difference between the steel stud to wood trusses significantly Thermographic testing done For the wall system reported in They attributed this to the holes The field performance appears to than at the cavity locations. mately 50% higher than the would keep the temperature switching from steel trusses stud locations were 4°C lower walls in houses was approxi- The discrepancy between foundations further lowered the Air Infiltration laboratory and field testing thermal performance of steel- prompted researchers at the framed walls relative to wood- The Energy Services Group Oak Ridge National Laboratory framed walls. Wood-frame con- from Wilmington Delaware, in Oak Ridge Tennessee to struction is clearly superior in terms noted in the August 1995 examine the effect windows, of overall thermal performance. T h e r m a l p e r f o r m a n c e o f L i g h t - F r a m e A s s e m b l i e s 9 Effects of Low Thermal Performance Ghost Marks on Steel Stud Walls US Steel conducted a series of on the exterior of the steel increased energy usage for the experiments in the early 1970s to framing members to reduce the heating and cooling of buildings. investigate the conditions that possibility of mould growth and The environmental effects of Ghost marks are unsightly dark cause ghost marks. They possible adverse health effects. increased energy usage due to vertical marks that appear over discovered that: the framing on the interior surfaces of exterior walls. A 1971 report from US Steel cited "ghost marks" caused by steel studs as "the single-most significant unsolved technical problem that prevents the general acceptance of steel studs in the residential market. The design of steel studs • Ghost marks occurred steel framing translates into a varied by more than 1.8°C, and Increased Construction Costs • Severe discoloration occurred Steel framing requires extra when the temperature at the foam insulation on the exterior steel stud was more than 4.5°C to achieve the same thermal colder than the cavity. resistance as wood-framed whenever the wall temperature systems. For example, foam has not changed, and ghost sheathing, 50 mm thick, is marking remains a problem. Contrary to common belief, poor thermal performance of Indoor Air Quality ghost marks are not caused by It is important to build differently moisture condensation and can with framing materials having occur even in a completely dry high conductivity such as steel environment. They are caused studs to avoid localised cold spots because floating dust particles at the thermal bridge. required to make a steel-framed wall thermally equivalent to a 38 x 140 mm wood-frame wall. There will also be an increased cost for the extra provisions such as extended window and door jambs. every direction absorb energy In a letter to the Environmental at a faster rate from warm air Building News, Sept./Oct 1995 than from a cool wall. As a edition, a Canadian researcher result, the dust particles are cautioned about the health impli- propelled towards the cool cations of mould growth at the wall surface. thermal bridge over steel studs. On a wall with a uniform surface Mould is the major indoor con- temperature, such as a wood- taminant in most homes. Local framed wall, dust accumulation cold surfaces in higher humidity is not noticeable since it spreads houses could result in serious evenly over the wall surface. But mould growth problems after on a wall with cold spots, such the first few cold months. as a steel-framed wall, dust accumulates faster over the colder areas and is visible as ghost marks. I n t e r n a t i o n a l Building series NO. 5 This cost is in the form of increased air pollution, increased CO2 emissions, and additional use of non-renewable fossil fuels. The use of foam sheathing to increase the thermal performance of steel-frame assemblies also has an environmental cost. Foam sheathing is derived from nonrenewable fossil fuels. The manufacture of some types of foam sheathing produces hydrofluorocarbons (HCFC) which cause ozone depletion and use high levels of energy. For example, it takes which are constantly moving in 10 cost that must be borne by society. The researcher reiterates the importance of reducing the cold spots by placing the insulation approximately 1600 kW-hr of Increased Energy Requirements and Environmental Costs In the Montreal area in Canada, for example, a small house with 90 m2 wall area with 38 by 89mm framing and RSI-2.3 batts, would use an estimated 2900 kW-h per year more if was framed with steel than if it was framed with wood. The lower thermal performance of steel framing results in energy to manufacture 100 m2 of 25 mm rigid foam, or enough to clad a 120 m2 bungalow. The additional environmental costs of the foam must be included when determining the environmental cost of the steel framing because the foam must be used to achieve the equivalent performance of the wood framing. Conclusion Energy requirements for • Construction methods buildings are increasingly for achieving thermal per important. The thermal formance with steel-framed performance of a building assemblies should be adjusted is becoming not only a to take into account the lower desired attribute but a field performance of the mandated code requirement assemblies, and in many jurisdictions. Recent research and experience • Steel framing requires addi- with wood and steel-framed tional insulation on the exterior systems have examined the of the framing to achieve the issue of thermal performance same insulation values as in detail. wood-framed assemblies. This summarises what has The consequences of not pro- Also, when wood framing is been learned to date about viding the additional insulation combined with proper construction the thermal performance of are higher heating and cooling techniques and materials including wood and steel-framed bills, ghost marks on the walls insulation, and air and weather systems: and deterioration of the indoor barriers, air leakages are mini- air quality due to increased mized resulting in a net decrease mould growth. in the energy consumption of • Laboratory research of clear walls shows that steel-frame the home over its lifetime. When walls have significantly lower Steel framing systems can be comparing a 1970 wood-frame thermal performance than designed to provide an equivalent house construction to an R-2000 wood-frame walls, thermal barrier but the provision wood-frame design, about half of the extra insulation results in • Field research shows that of the total improvement in increased material and environ- operating energy can be attributed steel-framed houses’ thermal mental costs for the system. to better envelope design. performance is worse than the Designers must consider the total laboratory tests predicted, performance and cost of a system In addition, wood is the only when making their choice. renewable building material, and • Computer modelling shows the production of wood products that the effect of construction Compared to steel and concrete, reduces industrial energy require- features such as intersections wood offers superior resistance ments and lowers the impact on with windows, doors and to heat flow because of its the earth’s environment. Wood- corners lowers the thermal unique cellular structure. Thus, frame buildings are also strong, performance of steel walls in a building envelope design, safe, warm, and cost efficient. even more than comparable wood framing loses less heat wood-framed walls which through conduction than other explains the difference between building materials. 11 laboratory and field research, T h e r m a l p e r f o r m a n c e o f L i g h t - F r a m e A s s e m b l i e s For more information please contact our office at: Canada Wood Head Office Website: www.canadawood.org Canada Wood China, Beijing Room 1507, Kuntai International Mansion, No.12 B Chaowai Street, Beijing 100020 Tel: (86-10) 5925-1255 Fax: (86-10) 5925-1258 Email: [email protected] Canada Wood China, Shanghai 425 Hong Feng Road, Pudong New Area, Shanghai 201206 Tel: (86-21) 5030-1126 Fax: (86-21) 5030-3241 Email: [email protected] Canada Wood Korea 3rd Fl., 203 Bldg., #203-7, Yangjae-dong, Seocho-gu, Seoul, Korea 137-893 Tel: (82-2) 3445-3835/4 Fax: (82-2) 3445-3832 Email: [email protected] Canada Wood France (Europe) 8 Esplanade Compans Caffarelli, 31000 Toulouse, France Tel: (33-5) 62-30-51-42 Fax: (33-5) 62-30-50-00 Email: [email protected] Canada Wood Japan Tomoecho Annex-11 9F 3-8-27 Toranomon Minato-ku Tokyo 105-0001, Japan Tel: (81-3) 5401-0531 Fax: (81-3) 5401-0538 Email: [email protected] Publications in this series: 1. 2. 3. 4. 5. Moisture and Wood-Frame Buildings Wood Trusses – Strength, Economy, Versatility Fire Resistance and Sound Transmission in Wood-Frame Residential Buildings Sustainability and Life Cycle Analysis for Residential Buildings Thermal Performance of Light-Frame Assemblies www.cwc.ca Canada Wood UK Suite 8, St-Albans House PO Box 1, Farnborough, Hants, United Kingdom GU14 6WE Tel: (44-1252) 522545 Fax: (44-1252) 522546 E-mail: [email protected] www.naturallywood.com A publication of the Canadian Wood Council. Funding support provided by Canada Wood partners: Canadian Plywood Association • Quebec Wood Export Bureau • SPF Group